The present invention relates to engine exhaust systems and, more particularly, to engine exhaust systems having exhaust cooling.
In many modern vehicles, such those including diesel engines, exhaust aftertreatment devices such as diesel particulate filters (DPF), selective catalytic reduction catalysts (SCR), and NOx traps are provided in the exhaust line downstream of the engine. Devices such as the SCR and NOx traps are typically disposed downstream of the DPF. It is periodically necessary to regenerate the DPF, which usually involves burning fuel upstream of the DPF to raise the temperature of the gas passing through the DPF to temperatures that are potentially harmful to other devices. To avoid damage to the downstream devices, it is customary today to control the temperature of the gas passing through the DPF, such as by reducing the amount of fuel burned to regenerate the DPF. Nonetheless, it is still possible to generate excess heat which can damage the downstream devices.
It is desirable to provide an apparatus and method that can reduce the potential for damage to aftertreatment devices downstream of a DPF.
According to an aspect of the present invention, an engine arrangement comprises an engine, an exhaust line downstream of the engine, an aftertreatment device in the exhaust line, and a conduit between a source of fluid and a point in the exhaust line upstream of the aftertreatment device.
According to another aspect of the present invention, a method of controlling temperature in an exhaust line is provided. According to the method, exhaust temperature in an exhaust line is measured at a point upstream of an aftertreatment device. A signal is sent to a controller corresponding to the measured temperature. Air is introduced to the exhaust line at or upstream from the measuring point under control of the controller as a function of the measured temperature.